Computer control of railroad train brake system operation

Abstract

Radio-based control of railroad train brakes is effected in which brake systems are computer controlled. An End of Train (EOT) system is used in which microprocessor circuits of a Locomotive Control Unit (LCU) and an EOT unit are programmed to perform these and other functions. The computer system has several states. On power on, the system enters the Setup state during which the system stores about one minutes worth of both brake pipe and equalizing reservoir pressure data. This data is later used to determine the rate of change of these pressures to determine stability. Once setup is complete, the system enters the Stability state during which operating pressures are determined. When the equalizing reservoir pressure, the brake pipe pressure and the brake pipe pressure at the end of the train are stable, the EOT unit is commanded to update operating pressures stored in its microprocessor control circuit. Once the several pressures have been found to be stable, the system goes to the Release state. The system makes transitions between the Release state and the Stability state until a predetermined decrease in brake pipe pressure is detected. At this point, the system makes a transition to the Application state. In this state, determinations are made as to whether to transmit brake commands to the EOT unit from the LCU or to return to one of the Stability or Release states. In any of these states, the system can immediately enter the Emergency state to the Setup state, if setup has not been completed, or to the Release state if setup has been completed.

We claim: 
     
       1. A locomotive and end of train telemetry apparatus wherein a Locomotive Control Unit includes means for transmitting signals to an End of Train Unit, and the End Train Unit has means for transmitting signals to the Locomotive Control Unit each under the control of a microprocessor located respectively in said Units, the microprocessor in said Locomotive Control Unit being provided with memory that stores brake pipe and equalizing reservoir pressure values occurring over a predetermined period of time as received from an equalization pressure reservoir and from a brake pipe extending continuously from the locomotive through a railway train of cars to a remote car of the train, the apparatus comprising: a System Interface Unit interfacing the microprocessor of the Locomotive Control Unit with the brake pipe and the equalizing reservoir for providing the microprocessor in the Locomotive Control Unit with said brake pipe and equalizing pressure values,   a pressure transducer interfacing the brake pipe with the microprocessor in the End of Train Unit for providing said microprocessor with brake pipe pressure values, and   the means for transmitting information between the Locomotive and End of Train Units includes respective radio transceivers electrically connected to the microprocessors located in the Locomotive and End of Train Units.   
     
     
       2. The apparatus of claim 1 wherein the memory of the microprocessor in the Locomotive Control Unit includes software that determines brake pipe pressure stability based upon changes in brake pipe pressure and equalizing reservoir pressure, as received by said microprocessor, occurring within a predetermined time span. 
     
     
       3. The apparatus of claim 1 wherein the End of Train Unit includes a valve pneumatically connected to the brake pipe at the location of said Unit and electrically connected to the microprocessor of said Unit, said valve being effective to control the exhaust of brake pipe pressure at either a service or emergency rate as may be remotely commanded. 
     
     
       4. The apparatus claim 1 wherein the System Interface Unit provided in the locomotive contains an algorithm that synchronizes microprocessor operations in the Locomotive Control and End of Train Units by forwarding time stamps to both of said microprocessors. 
     
     
       5. The apparatus of claim 1 wherein the microprocessors have a setup program that orders an emergency state if brake pipe pressure decreases at a predetermined rate. 
     
     
       6. A computer implemented method for radio-based Electro-Pneumatic (EP) control of railroad train brakes, said method being implemented on microprocessor control circuits of a Locomotive Control Unit (LCU) and an End of Train (EOT) Unit in an end of train system, the method comprising the steps of: on the occurrence of powering the end of train system, storing brake pipe and equalizing reservoir pressure data for a predetermined time period, said data later being used to determine a rate of change of brake operating pressures,   measuring rates of change of operating pressures to determine when equalizing reservoir pressure, brake pipe pressure and brake pipe pressure at the end of the train are stable;   when the equalizing reservoir pressure, the brake pipe pressure and the brake pipe pressure at the end of the train are stable, commanding the EOT unit to update operating pressures stored in its microprocessor control circuit;   detecting a predetermined amount and rate of decrease in brake pipe pressure indicating application of brakes; and   transmitting brake commands from the LCU to the EOT Unit in response to detecting said predetermined decrease in brake pipe pressure.   
     
     
       7. The method of claim 6 including: monitoring brake pipe pressure to detect an emergency condition; and   immediately entering an emergency procedure upon detection of the emergency condition even if brake operating pressures have not been established.   
     
     
       8. The method of claim 7 wherein the method is implemented as a state machine on the microprocessor control circuits of the LCU and the EOT Units, the state machine entering a Setup state on the occurrence of power on to establish brake operating pressures and a Release state when operating pressures are established and stable, further comprising the steps of: detecting when an emergency condition ceases to exist; and   exiting from the emergency state to the Setup state or to the Release state if the Setup state is completed.   
     
     
       9. A method of implementing a setup state on a microprocessor located in a Locomotive Control Unit and in anEnd of Train Unit in an end of train system having a brake pipe extending between a locomotive and the last car of a train of cars connected to the locomotive, comprising: commencing a setup state on the occurrence of powering the end of train system to establish brake pipe pressure and a brake release state when brake pipe pressure is established and stable by determining the magnitude and a rate of change in brake pipe pressure,   detecting an emergency condition if the magnitude in brake pipe pressure decreases at a predetermined rate, and   completing the setup state if brake pipe pressure increases to a predetermined magnitude after a predetermined period of time.   
     
     
       10. The method of claim 9 further including: determining pressure magnitude in an equalization reservoir connected to the brake pipe after a predetermined period of time has elapsed to complete the setup state.   
     
     
       11. A method of determining a state of stability in brake pipe pressure values in a train of cars connected to a locomotive, the locomotive and cars having a brake pipe extending from the locomotive to and through the cars to a car remote from the locomotive, comprising: determining a change in pressure values in a brake pipe at the locomotive and at a car of the train remote from the locomotive, as well as a change in the pressure value of a equalization reservoir connected to the brake pipe,   determining if the brake pipe and equalization reservoir pipe pressure values are at or below a predetermined rate of change, in which case a state of stability exists for releasing the brakes of the train, and   updating said pressure values using software associated with a microprocessor respectively located in the locomotive and in the car remote from the locomotive, and respectively connected to the brake pipe at the locomotive and in the car remote from the locomotive for receiving pressure values existing in said brake pipe.   
     
     
       12. A method of providing a state of release for the brakes of a train of cars connected to a locomotive, comprising: determining a rate of change in the magnitude of pressure in a brake pipe extending from the locomotive to and through said cars,   providing a state of pressure stability if said rate of change is less than a predetermined value,   using said pressure stability to release the brakes of said train, and to thereinafter apply said brakes when needed.   
     
     
       13. A method of qualifying the brakes of a train of railroad cars for minimum brake application, said train having a brake pipe and an equalizing pressure reservoir, the method comprising: determining pressure and a rate of pressure change in the brake pipe and equalizing pressure reservoir,   determining pressure in the equalizing pressure reservoir if the rate of change in brake pipe pressure is less than the predetermined amount over said predetermined period of time,   forwarding a minimum brake application command to a car located at an end of the train remote from a lead locomotive connected to the train of cars if the pressure in the equalizing pressure reservoir has increased more than a predetermined amount in a predetermined period of time, and   decreasing brake pipe pressure at the remote end of the train upon receipt of the command in the remote car.   
     
     
       14. A method of qualifying service application of the brakes of a train of railroad cars comprising: measuring a rate of change in the magnitudes of equalization reservoir pressure and brake pipe pressure, and   sending service brake commands to an End of Train Unit of railroad cars if there has been a predetermined decrease in equalizing reservoir pressure in a predetermined period of time.   
     
     
       15. The method of claim 14 further including: monitoring an equalizing reservoir pressure signal provided upon the occurrence of a brake release state to determine if the brakes of the train are released or applied.   
     
     
       16. The method of claim 14 further including: declaring the equalization reservoir pressure stable if the magnitude of equalizing reservoir pressure decreases less than a predetermined amount within a predetermined period of time and either does not increase in pressure in a predetermined period of time or increases in pressure a minimal amount in a predetermined period of time.   
     
     
       17. The method of claim 16 including the further step of exiting to a Qualify Deeper Service Application state when the equalizing pressure reservoir signal is declared stable. 
     
     
       18. The method of claim 14 further including: calculating a target brake pipe pressure reduction at the End of Train Unit when said Unit receives a service brake command, and venting brake pipe pressure until said pressure reaches the calculated target pressure.   
     
     
       19. The method claim 14 further including: forwarding a brake release command to the End of Train Unit when a change in equalizing reservoir pressure indicates a change from brake applied to brake release, and   relinquishing control of brake pipe pressure by the End of Train Unit when the brake release command is received by said End of Train Unit.   
     
     
       20. The method of claim 14 further including: synchronizing the operation of the End of Train Unit with a Locomotive Control Unit using time stamps issued by a System Interface Unit interfacing brake pipe pressure with a microprocessor in the Locomotive Control Unit,   forwarding said time stamps to said microprocessor from the System Interface unit, and   transmitting said time stamps from said microprocessor to a microprocessor located in the End of Train Unit.   
     
     
       21. A method of effecting a self-test procedure for determining pneumatic conditions at the end of train of railroad cars having an End of Train Unit containing a microprocessor and associated memory, said associated memory containing self-test software, the method comprising: initiating the self-test procedure by running the software,   using said software to provide a self-test pressure value and to set the same to a service brake pressure value,   determining if the value of the service brake pressure is less than the self-test pressure value by a predetermined amount, and   indicating a FAIL condition if the service brake pressure value is less than the self-test pressure valve by the predetermined amount.   
     
     
       22. The method of claim 21 further including: starting a self-test timer to run for a predetermined period of time, determining whether or not said timer has timed out if service brake pressure value is not less than the self-test pressure value by said predetermined amount, opening a release service valve for a predetermined period of time when the timer has timed out, setting again the self-test pressure value equal to the service brake pressure value, closing said release service valve, and opening a supply/exhaust service valve.   
     
     
       23. The method of claim 22 further including: determining again if the service brake pressure valve is less than said self-test pressure value by a predetermined amount, and indicating a PASS condition if the service brake pressure value is not less than the self-test pressure value by said predetermined amount.   
     
     
       24. The method of claim 21 further including: using a System Interface Unit connecting a brake pipe and an equalizing pressure reservoir to a Locomotive Control Unit to order the self-testing procedure for the end of the train having the End of Train Unit.   
     
     
       25. A method of making minimum incremental reductions in brake pipe pressure at an End-of-train Unit in proportion to a decrease in pressure in an equalizing pressure reservoir connected to a brake pipe at the locomotive end of the train, which pipe extends to the End-of-train Unit, the method comprising: sending electronic instructions from the locomotive end of the train to the End-of-Train Unit concerning the reduction in reservoir pressure before a reduction in brake pipe pressure takes place at the locomotive end of the train and propagates to the End-of-Train Unit from the locomotive end, and   reducing brake pipe pressure at the locomotive end of the train based on the reduction in reservoir pressure.   
     
     
       26. The method of claim 25 including: synchronizing the reductions in brake pipe pressure at the locomotive end and at the End-of-Train Unit by providing the locomotive and End-of-Train Unit with timers that time stamp incremental brake commands generated at the locomotive end and at the End-of-Train Unit.   
     
     
       27. The method of claim 25 including: using a Service Interface Unit connecting the brake pipe to a microprocessor in the locomotive to synchronize the brake pipe reductions in pressure at the locomotive end and at the End-of-Train Unit.   
     
     
       28. The method of claim 27 including: using said Interface Unit to update operating pressures in the reservoir and brake pipe, and   synchronizing brake pipe reduction in pressure when said operating pressures are updated.   
     
     
       29. The method of claim 28 including: sending a synchronized command to the End-of-Train Unit from the Interface Unit, and   using the End-of-Train Unit to synchronize itself to said command.   
     
     
       30. The method of claim 25 including: determining if a minimum brake application command has previously been received by the End-of-Train Unit when said Unit receives a current minimum brake application command, and   refusing to perform the current brake application if a previous minimum brake application in the End-of-Train-Unit has been received by the End-of-Train-Unit.   
     
     
       31. The method of claim 30 wherein the End-of-Train Unit looks for the value of brake pipe pressure at the time the minimum brake application command was generated if a previous minimum brake application has not been received by the End-of-Train Unit, and refuses to make the minimum brake application of the command if current brake pipe pressure is greater than or equal to a predetermined amount below the brake pipe pressure at the time the command was generated. 
     
     
       32. The method of claim 31 wherein the end-of-train unit performs the minimum brake application if a previous brake application has not been received, and if current brake pipe pressure is not greater than or equal to said predetermined amount below the brake pipe pressure when the command was generated.